The present invention relates to a surgical apparatus and method for occluding or encircling a body passageway such as a blood vessel. The invention further relates to surgical clips suitable for use in such an apparatus and method. The word xe2x80x9csurgicalxe2x80x9d herein includes human and veterinary surgery and the word xe2x80x9cpatientxe2x80x9d herein includes human and animal patients.
The word xe2x80x9coccludingxe2x80x9d herein includes complete or partial closure of a body passageway and the word xe2x80x9cencirclingxe2x80x9d herein includes prevention of expansion of a body passageway without application of a constrictive force.
The surgical control of bleeding (haemostasis) by the closing of blood vessels is one of the oldest and most fundamental principles of surgery. Modern techniques such as minimally-invasive surgery cannot be performed without effective haemostasis, but there are significant difficulties in that the surgical instruments have to be controlled remotely from an operating zone within a patient and the surgeon is typically viewing the operating zone via an endoscope.
It is known to perform haemostasis during an endoscopic minimally-invasive surgical procedure by means of single sutures or ligatures tied around individual blood vessels. It is also known to use clips in the form of V-shaped lengths of silver wire which are cramped across the blood vessels. Sutures and ligatures are slow to apply as stitching or tying of individual threads is required, and the securement is technically difficult in endoscopic surgery. Silver clips are prone to dislodge.
Endoscopic staples are also Cloven for the occlusion of larger body passageways such as bronchi, the bile duct or bowel, but are too large for use on individual small vessels. Sprung clips have been used to occlude aortic aneurysms in conventional open (non-endoscopic) surgery, but are too large for use in endoscopic minimally-invasive surgery.
Thus, for example, U.S. Pat. Nos. 5,02,6379, 5,217,473 and 5,226,908 (Yoon), the disclosures of which are incorporated herein by reference, describe a ligating and occluding clip, useful in surgical sterilisation and other techniques, in which two straight legs are joined so that an elastic closing force closes the legs together across an anatomic tubular structure. These U.S. patents also describe an applicator device which releases the clip, legs splayed apart, onto the anatomic tubular structure. The elastic closing force causes the legs to close onto, and clamp, the anatomic tubular structure.
U.S Pat. Nos 3,675,688 and 3,735,762 (Bryan et al), the disclosures of which are incorporated herein by reference, describe a metal ligating and occluding staple which is wrapped around an anatomic tubular structure to occlude the same, as well as a cartridge applicator device from which staples are dispensed and which includes parts which cause each staple to be wrapped around the anatomic tubular structure and subsequently sever the structure.
U.S. Pat. No. 4,950,258 (Kawai et al), the disclosure of which is incorporated herein by reference, describes a range of surgical articles moulded from shape memory plastics, the articles including cerebral aneurysm clips (FIGS. 7 and 8a-8d) and a haemostatic clip (FIGS. 12a and 12b) which generally have two straight legs joined so that the shape memory effect causes a closing force to be exerted to close the legs together from a splayed apart condition (in which an anatomic tubular structure can be located within the clip) to a parallel condition (in which the anatomic tubular structure is constricted). The plastic material is biodegradable.
Apart from the biodegradability of the plastic material, which limits its utility to operations where only temporary occlusion or encircling of a body passageway is required, the surgical articles of U.S. Pat. No. 4,950,258 have a number of other disadvantages. The closing force is not particularly strong, so that the shape memory induced closure of the clips is slow and unreliable. Moreover, the straight-legged clips are unworkable in a confined operating zone. Still further, no practical applicator device is disclosed.
Other shape memory materials are known, which have been tested for use in the surgical occlusion or encircling of body passageways.
WO-A 92/13490 (Friedland), for example, describes a surgical fastening clip of a substantially U-shaped member of a shape memory metal alloy (eg Nitinol). The clip has an austenitic transformation temperature in the range of 30 to 35xc2x0, i.e just below normal body temperature. A range of clip designs is illustrated. FIG. 4, for example, shows a clip generally having two straight legs joined to form the general U-shape. In FIGS. 15 and 16, the legs are each kinked into a zig-zag shape. In FIGS. 20 and 21 the low temperature shape is straight-legged, the zig-zag shape appearing only in the austenitic state. A general feature of the clips is that in the austenitic shape the legs are tightly clamped together. The description teaches that the clips are to be squeezed down onto a vessel or tissue in the niartensitic (low temperature) state, whereupon heating to body temperature is allowed to occur to change the alloy to its austenitic state and xe2x80x9clockxe2x80x9d the clip into the clamping condition (see, e.g. page 18, line 23 to page 19, line 7).
The disclosure of WO-A-92/13490 does not fully answer the needs of surgeons. The closing force of the clips is too small to be usable as an active occlusion and encircling system in a surgical procedure, i.e. where the clip itself closes onto a body passageway rather than being squeezed onto the body passageway by some external force. The need for an external force inherently limits the applicability of the prior art clips to surgical procedures where a clamping device can gain access to the operating zone. In any event, the disclosure does not clearly teach an applicator device whereby the clips can be located in place in a real surgical procedure and the transition from the martensitic to the austenitic states controlled in the body temperature environment of an operating zone within a patient""s body.
U.S. Pat. No. 5,601,572 (Middleman et al), the disclosure of which is incorporated herein by reference, describes a surgical use of pseudoelastic shape memory alloys in which the memorised physical deformation takes place without additional squeezing or other pressure, and is an essential feature of the operation of a surgical instrument. xe2x80x9cPseudoelasticityxe2x80x9d is a behaviour exhibited by shape memory alloys in a stress-induced martensitic condition. The instruments disclosed include a variety of devices in which generally an elongate member formed of a shape memory alloy is housed under stress within a hollow shaft of the instrument and extended from/retracted into a distal end of the shaft at an operating zone within a patient. In its extended condition the elongate member adopts its xe2x80x9cmemorisedxe2x80x9d shape, to perform a variety of surgical tasks.
In FIGS. 1-4 to 1-12 of U.S. Pat. No. 5,601,572, for example, and in the description accompanying those figures, a surgical instrument is illustrated and described, in which an elongate pseudoelastic shape memory alloy member is used to secure a ligature about a blood vessel, by extending the member from, and retracting it into, the hollow shaft of the instrument. The procedure is slow and complex, as well as being difficult to control in a confined operating zone.
WO-A 98/58591 (Boston Scientific Corporation; filed Jun. 17, 1998; published Dec. 30, 1998), the disclosure of which is incorporated herein by reference, describes a haemostatic clip formed of a material exhibiting pseudoelastic behaviour at body temperature. Such materials include shape memory alloys when in a stress-induced martensitic condition, and this reference describes the use of generally U-shaped staple-like haemostatic clips of such alloys which are individually held under stress with the legs of the clip forced into parallel alignment, at body temperature in an applicator device described as a xe2x80x9chypotubexe2x80x9d (See FIGS. 1 to 5 and associated description). Upon release from the hypotube onto a blood vessel, the legs of the clip close together as the austenitic phase predominates and the memorised shape is adopted. A corresponding circular clip is illustrated in FIGS. 8 to 11, the clip being initially held confined in a curved hypodermic needle to stress-induce the martensitic condition. The closure of the clip is triggered by release of the stress, with no change in temperature.
The clips and applicators disclosed in WO-A-98/58591 suffer from a number of disadvantages. A prime difficulty is that a relatively complex applicator ejection system is required, because of the need to maintain the stored clip under stress before discharge.
This makes the applicator unwieldy, the release operation difficult for the surgeon, and limits the extent to which multiple clips can be loaded into the applicator for repeated use during a surgical procedure.
Therefore, no effective and secure method for occluding or encircling body passageways has been available hitherto which satisfies the requirements of (a) being usable on a wide range of body passageways from small blood vessels to large ducts, (b) being quick and easy to execute in all procedures, including open, micro and endoscopic procedures, and (c) being at least as reliable as the conventional methods.
The present invention aims to go at least some way towards meeting these requirements, or at least to provide an effective alternative to the known methods.
The invention is based on the finding that a clip, comprising an elongate element having first and second ends and being resiliently movable under an inherent biassing force between a first configuration in which the ends are spaced apart to allow a body passageway to pass therebetween and a second configuration in which the elongate element is deformed, preferably generally helically wound, on itself so that the clip grips or encircles the body passageway, can be released or offered towards the body passageway in the first configuration using a clip dispensing apparatus, whereupon the clip resiliently deforms itself around the body passageway to encircle and optionally constrict and occlude the same. The expressions xe2x80x9chelicalxe2x80x9d and xe2x80x9cgenerally helically woundxe2x80x9d, used herein, refer to at least one end of the clip bending inwardly around the body passageway, preferably to a condition where the ends are overlapping or crossing one another at least to some extent, and in particular are not to be considered as limited only to circular or cylindrical configurations
Temperature-responsive shape memory materials, e.g. Nitinol alloys (nickel-titanium), are preferably to be used for this purpose. The preferred form of the present invention differs, however, from the prior art in that the transformation on which the shape memory is based is or includes the temperature-induced martensitic to austenitic transformation, as opposed to only the pseudoelastic or stress-induced martensitic to austenitic transformation. In particular, the clip is held in the dispensing apparatus at a temperature substantially below body temperature, and it is the body temperature of the operating zone that triggers closure of the clip. In addition, a novel clip shape is preferably employed, yielding substantial benefits in occlusion efficiency, and a novel applicator is also provided, in which preferably the thermal characteristics, for example conductivity, of the operating mechanism of the applicator itself contributes positively to the functioning of the clip.
The various features of the invention are as set forth in the claims appended hereto, allowing for any principles of interpretation of those claims as prescribed by law.
Thus, in a first aspect of the present invention, there is provided a surgical apparatus for occluding or encircling a body passageway, the apparatus generally comprising:
(a) a housing holding one or a plurality of clips of the type described above in the first configuration thereof, the housing having a port through which an individual clip can be released to occlude or encircle the body passageway;
(b) a drive member disposed within the housing and movable therein to urge a clip within the housing towards the port thereof, and
(c) a clip control device associated with the drive member and operable externally of the housing to control the movement of the clip therein and expulsion of the clip therefrom.
The clip control device is so arranged and/or the port of the apparatus is so configured that only one clip can pass through the port in any one operation of the clip control device.
Particularly when the apparatus is to be used in endoscopic surgery, the housing suitably comprises a hollow shaft having a proximal end and a distal end, the port being provided at or near the distal end and a handle being provided at or near the proximal end, in general proximity to the control device, whereby a surgeon can hold the apparatus.
It is preferred, although not essential, that the clips are held in a line within the hollow shaft of the housing and driven in that line towards the open distal end. Alternatively, for example, they can be held in a magazine and fed into the shaft one by one by clip feeding means. The clips are conveniently provided as a train of generally like clips, all similarly oriented in the train. In some cases, the clips can conveniently be mutually frangibly connected to form a cartridge which can be loaded into the shaft or magazine. A guide member may suitably be provided in the housing, which guide member supports the clip(s), slidably within the housing, in a location whereby the drive member can urge the clip(s) towards the port of the housing.
When referring to the elongate element of the clips for use in the device of the present invention, the expression xe2x80x9cresilientxe2x80x9d and like expressions used herein shall be taken to refer to all forms of inherent or internal (molecular) biassing of the elongate element of the clip towards its second configuration. For example, a biocompatible temperature-responsive xe2x80x9cshape-memoryxe2x80x9d material can be used, in which the resilience is activated by a change (typically a rise) in temperature, so avoiding the need for the clip to be held in its first configuration against a restoring force. The xe2x80x9cmemorisedxe2x80x9d shape will be the second, e.g. helical, configuration. The xe2x80x9cshape-memoryxe2x80x9d material may, for example, be a metallic alloy such as Tixe2x80x94Ni, Nixe2x80x94Al, Agxe2x80x94Cd or Auxe2x80x94Cd, a norbornene polymer, a nematic liquid crystal polymer, or an advanced thermoplastic elastomer such as a homopolymer of lactide or glycolide or copolymers thereof. For further discussion of these materials, please refer to U.S. Pat. Nos. 3,442,871, 3,797,499, 3,839,297,4,505,767,4,523,591, 4,603,695 4,935,068 and 4,950,258, as well as British Patent No. 1040168 (the disclosures of all of which are incorporated herein by reference), in addition to the prior art acknowledged above.
In summary, and as will be well known to those of ordinary skill in this art, shape memory alloys are capable of transforming between martensitic and austenitic phases. This transformation between phases can be caused by a change in temperature. For example, a shape memory alloy in the martensitic phase will begin to transform to the austenitic phase when its temperature rises above the austenite start temperature As, and the transformation will be complete when the temperature rises above the austenite finish temperature Af. The transformation from austenitic to martensitic will begin when the temperature drops below the martensite start temperature Ms, and will be complete when the temperature drops below the martensite finish temperature Mf. The temperatures Ms, Mf, As and Af define the thermal transformation hysteresis loop of the shape memory alloy, and can be adjusted with a relatively high degree of precision, in the case of Tixe2x80x94Ni alloys by adjustment of the relative proportions of the nickel and titanium.
The preferred material is a biocompatible and magnetic resonance imaging (MRI-) compatible temperature-dependent shape memory material having a shape transition temperature (martensite-to-austenite) in the range of approximately 20-35xc2x0 C. This means that Af should be no greater than about 35xc2x0 and As, should preferably be no less than about 20xc2x0 C., e.g. less than about 15xc2x0 C. Such a material is Nitinol, which is a nickel-titanium alloy comprising approximately 50 atomic percent nickel. For example, the alloy may be a binary alloy consisting of 50.8 atomic percent nickel and 49.2 atomic percent titanium, or it may include a quantity of a third element such as copper, cobalt, vanadium, chromium or iron. The binary alloy is preferred, as the more complex systems generally have inferior biocompatability.
Alternatively, however, a temperature-dependent shape memory plastic of the types disclosed in the acknowledged prior art can be used.
Such clips should be stored in the martensite phase at a reduced temperature (preferably below about 20xc2x0 C., e.g. below about 15xc2x0 C.), so that, on deployment into the operating zone within the patient, the patient""s body temperature rapidly heats the clip to a temperature above the martensite-to-austenite shape transition temperature, preferably above Af. This has been found to impart a closing force of up to 200 grams force onto the body passageway as the ends of the clip close to the second configuration of the clip. In this way, the closing force can be tailored to the intended end use of the clip, e.g. a crushing force (for haemostasis, for example) or a non-crushing force (for occluding body ducts, e.g. in sterilisation).
At least the central portion of the clip, between the ends thereof, is preferably formed of the resilient material. Preferably the whole clip is formed of the resilient material.
The said central portion of the elongate element of the clips is typically in the range of about 1 to 30 mm in length, depending on the intended use of the invention. The arrangement should preferably be such that in use the elongate element twists, e.g. helically, around a body passageway to match the size of the body passageway (encircling) or with a sufficient constrictive force thereon to occlude (at least partially close) the body passageway. The selection of the precise material and dimensions of the elongate element for this purpose will be well within the capabilities of one of ordinary skill in this art.
The first and second ends of the clip preferably comprise legs extending in the same general direction as each other from the intermediate central portion, the intermediate central portion being most preferably convoluted as will be described in more detail below. The term xe2x80x9cgenerally the same directionxe2x80x9d used herein refers to directions which are broadly similar, i.e. less than about 120xc2x0 separated, preferably less than about 45xc2x0 separated. This configuration will be referred to herein as a generally U-configuration.
The clips are very convenient for surgical placement, achieving potentially up to about twice or three times the opening distance of conventional surgical clips. It is most preferred that the ends of the legs of the clip in the first configuration thereof should be spaced apart by no more than about 4 times the external diameter of the body passageway, more preferably no more than about 3 times the said diameter, and most preferably between about 1.5 and about 2.5 times the said diameter.
The legs of the clip in the first configuration thereof may be straight or curved, or may have straight and curved regions along their length.
The ends of the elongate element of the clip may conveniently be somewhat enlarged so that the clip in a fully straight configuration (which is not necessarily achievable in practice but may be only theoretical) would have the general appearance of a miniature weightlifter""s dumbbell. The surfaces of the ends of the elongate element of the clip may be formed of a tough, low-friction, high-abrasion-resistance material such as, for example, ultrahigh molecular weight polyethylene. The ends of the clip can slide over each other, optionally with a cam action, as the clip deforms into its second (helical) configuration. The folded-over ends of the clip are thus securely fastened in the second configuration to encircle or constrict the body passageway.
The elongate element of the clip between its ends may, for example, be of generally cylindrical, rectangular, triangular or square cross-section.
In a particularly preferred form, the tightness of the helical winding is such that the diameter of curvature is less than about 2 mm. It is preferred that the elongate element should not close on itself completely, as this would carry a risk of severing the body passageway. The extent of closure will be readily selectable according to the dimensions and materials of the clip, and this is well within the abilities of one or ordinary skill in this art.
The clips may be permanent in the sense of non-absorbable by the patient""s body, or biodegradable (absorbable) within the patient""s body.
In their first configuration, the clips may, for example, be aligned longitudinally (end-to-end) or transversely (side-by-side). Where the first configuration of the clips is a generally U-configuration, the clips may be in chevron alignment nested together.
The preferred clip shape will now be described in more detail.
In the first (low temperature) configuration, the clip may suitably be in the general form of a staple, and preferably has a convoluted, e.g. a zig-zag or sinuously curved, central portion, formed preferably of Nitinol wire, e.g. of substantially circular cross section. For a clip having legs approximately 2 mm apart in the first configuration the Nitinol wire may suitably have a cross-sectional diameter of approximately 0.3 mm, and correspondingly larger or smaller clips will use correspondingly thicker or thinner wire. The convoluted central portion has at least one, preferably two, three or more, apices directed towards the legs of the clip. These apices provide shoulders against which the legs in the second (body temperature) configuration can urge the body passageway.
The convoluted central portion has the further desirable property that it permits the central portion of the clip to expand sideways slightly in the second configuration (e.g. by a flattening of the sinuous curves) so allowing the legs to clasp towards the central portion of the clip with a good angular presentation and therefore good mechanical advantage.
The legs of the clip are preferably integral with the central portion and consist of the same Nitinol wire, extending in generally the same direction as each other in the first configuration of the clip and lying preferably in substantially the same plane as the convolutions of the central portion. In the first configuration of the clip, the legs preferably turn slightly mutually inwards and at their ends they are preferably each provided with a wedge surface with suitably terminates to a wedge apex line at the end of the respective leg. This wedge apex line may suitably be approximately parallel with the corresponding wedge apex line of the opposing leg of the clip.
A little way along each leg from the terminal wedge surf ace there may suitably be provided an enlarged inwardly directed nip-head projection, which may for example be rounded. This nip-head projection is arranged to bear towards one of the inwardly directed apices of the convoluted central portion of the clip in the second configuration of the clip, to maximise the pinching effect of the closure of the legs towards the central portion as the clip moves into the said second configuration.
In moving towards the second configuration of the clip, the convolutions (e.g. the zig-zag or sinuous curve) of the central portion of the clip may straighten somewhat, accompanied by a slight reduction in the amplitude of the zig-zag or sinuous curves (e.g. by about 0.1 to about 2 percent) and the legs close towards each other so that the wedge surfaces slide over one another. For this purpose, the wedge apex lines may suitably be slightly offset from one another out of the plane of the clip in the first configuration, so that they will not meet each other precisely square-on during the closing movement. In addition, the closing movement involves the ends of the legs moving towards the central portion, so that the nip-head projection of each leg urges the body passageway towards an inwardly directed apex of the convoluted central portion. This movement of the ends of the legs inwards towards the central portion may suitably have the effect of reducing the external dimensions of the clip (back of the central portion to front of the legs) by approximately 10 to 80%. Where the body portion has a zig-zag or sinuous curve, the percentage reduction in the dimension of the clip may be towards the lower end of the range, e.g. about 10 t o 30%, as the amplitude of the zig-zag or sinuous curve may itself constitute up to about 40 to 50% of the dimension, and this amplitude typically changes only marginally as the convolutions of the central portion straighten slightly, as described above.
As will be well known to those skilled in the art, the clips of the present invention will suitably be first formed in their second (austenite) configuration, e.g. by cutting and press-forming the Nitinol wire and bending the resulting form to shape, and the temperature is then lowered to below the austenite-to-martensite transition temperature (i.e. to below Mf). The alloy atomic structure changes to the weaker martensite form, and the material can easily be deformed to a new shape, namely the first configuration.
Martensitic transformation comes about not through nucleation and growth (as in most crystal structure transformation of metals and alloys). Instead, it occurs through a much faster collective shear process, The transformation of interest in the present invention is the temperature-induced martensitic transformation. The alternative possible stress-induced or mechanical martensite transformation, and the pseudoelasticity and superelasticity that it produces, is not necessarily a requirement of the present invention.
It is an important preferred feature of the apparatus that the distal clip, prior to expulsion from the apparatus, is held in the port of the housing in its first (open) configuration, adjacent to the body passageway to be occluded or encircled and in such a way that the ends of the clip are free to deform onto the body passageway without external pressure to close the clip. Once the closing movement has sufficiently advanced, the apparatus can be withdrawn, without any internally driven propulsion of the clip from the housing. The expression xe2x80x9cexpulsionxe2x80x9d or xe2x80x9cexpelledxe2x80x9d used herein to describe the dispensing of the distal clip from the apparatus, includes all forms of release, including passive dispensing in this sense, i.e. the withdrawal of the apparatus from the operating zone so as to leave the clip in place on the body passageway.
The housing of the apparatus holds and supports one or more, preferably a plurality, of the clips in the first configuration thereof. The plurality of clips may be in a line with the clips aligned longitudinally (end-to-end) or transversely (side-by-side). Alternatively, a plurality of generally U-configuration clips may be in a chevron-like line. An even number of clips may suitably be used, particularly for procedures where body passageways need to be occluded at two points along their length. This prevents accidental exhaustion of the supply of clips during the procedure.
Certain clips in the first and/or second configurations thereof are novel, irrespective of whether the material from which the clip is constructed is a temperature-responsive shape memory material or any other resilient material such as, for example, a conventional elastomer. These clips constitute further features of the present invention, and while their presentation to a body passageway may be accompanied by a rise in temperature as the clip warms to the temperature of the operating zone, this temperature rise is not an essential pre-requisite for the closing of such clips into the second configuration thereof.
Thus, according to a further aspect of the invention, there is provided a surgical clip for occluding or encircling a body passageway, the clip comprising an elongate element having first and second ends and an intermediate central portion, the clip comprising a resilient material and being resiliently movable under an inherent biassing force from a first configuration, in which the ends are spaced apart to allow the body passageway to pass therebetween, to a second configuration in which the clip is deformed, preferably generally helically wound, on itself so that the clip grips or encircles the body passageway, wherein:
(a) the first and second ends of the clip are legs which in the second configuration of the clip are turned inwardly toward the intermediate central portion of the clip, whereby the body passageway is gripped between the legs and the intermediate central portion of the clip, or encircled by the legs and the central portion of the clip, the intermediate central portion being convoluted in at least the said second configuration;
(b) the first and second ends of the clip are adapted, for example enlarged, so that in moving from the first to the second configuration the ends of the clip can slide over each other, optionally with a cam action, as the clip deforms into its second configuration;
(c) the first and second ends of the clip are legs which are provided with enlarged nip-head projections along their lengths, whereby in the second configuration of the clip the projections nip the body passageway against the intermediate central portion of the clip;
(d) the first configuration of the clip is substantially rectilinear and the second configuration of the clip is preferably generally helically wound on itself, whereby if the clip comprises an elastomeric material, the first configuration is achievable by holding the clip constrained in the said rectilinear configuration against a resilient restoring force tending to move the clip into the second configuration thereof; or
(e) any combination of (a) to (d) above.
The housing preferably comprises a thermally insulating hollow shaft containing the clips and the drive member, the port being an open distal end of the shaft. In this preferred form of the invention, the cover member for the port is preferably a thermally insulating cup or thimble arrangement which can be manually removed for use, and replaced when the apparatus is not in use. This cover member is desirable so that temperature-responsive clips in the housing do not warm up prematurely.
Alternatively, the cover member may be moved into and out of position by use of a cover member control device operable externally of the housing. In a preferred form of such an arrangement, the clip control device and the cover member control device are synchronised and actuable by a single action of the surgeon. In such an arrangement, the cover member for the port of the housing preferably takes the form of a retractable shutter, movable back and forth in response to actuation of the cover member control device. The shutter preferably has a closed portion which serves to cover the port of the housing when the closed portion and port are correspondingly aligned and an open portion which serves to uncover the port when the open portion and port are correspondingly aligned. By providing a retractable cover member at the port of the housing, and by synchronising the clip control device and cover member control device so that the drive member of the apparatus can only operate on the clips when the port is covered, there is no possibility of causing more than one clip to become available to be released through the port in on xe2x80x9cfiringxe2x80x9d (i.e. actuation) by the surgeon.
In a preferred form of the invention, therefore, the apparatus further comprises:
(d) a cover member for the port of the housing, the cover member being movable selectively to cover or uncover said port; and optionally
(e) a cover member control device operable externally of the housing to control the movement of the cover member and thereby the expulsion of the clip from the housing.
The apparatus preferably includes a temperature control device for maintaining the clip(s) at the first temperature within the housing. The temperature control device may include a thermostat, for automatic fine control of temperature within the housing. Suitable temperature control devices include electronic semiconductor-based cooling devices which use the Peltier effect, or gas-expansion-based cooling devices which use the Joule-Thompson effect. The parts of the clip drive and control means which support and contact the clips may suitably be thermoconductive (e.g. metallic), and in thermal contact with the temperature control device, whereby the temperature of the clips themselves can be effectively controlled.
The drive member for urging a clip within the housing towards the port thereof suitably comprises a push member (e.g. a pressor rod) disposed at least partially upstream of the clips to be slidable within the housing to urge against the line of clips within the housing. The push member is preferably spring biassed. The distal clip preferably lies in an expulsion station adjacent the port, from which it can be released from the apparatus either by its own inherent tendency to twist out of its holding alignment or by an expulsion element provided in the apparatus. For example, an expulsion element may be required to break any frangible connections in a cartridge of clips. The line of clips is preferably oriented about its axis in such a way that the ends of the distal clip will tend to move (twist) away from the port of the apparatus and around any adjacent body passageway.
The clip control device of the apparatus are preferably manually operable by the surgeon (e.g. by finger pressure on a button or trigger). The control of clip movement and expulsion is of great importance to the success of the apparatus, as the consequences of incorrect xe2x80x9cfiringxe2x80x9d of the apparatus would be catastrophic for a patient.
The clip control device of the apparatus preferably comprises a ratchet or cam device associated with the push member and operably linked to the remainder of the clip control device. In one preferred form, a spring forwardly biasses the push member, the spring being releasable from contact with the push member, and the ratchet or cam device serves in each actuation of the clip control device to take the spring out of contact with the push member when the port is open, thereby removing any spring-loaded forward pressure on the clips while the port is open. In another preferred form, a spring rearwardly biasses the push member, and the ratchet or cam device serves in each actuation of the clip control device to urge the push member in the forward direction (against the restoring force of the spring), which again serves to locate the distal clip in the port of the housing without any forward pressure on the clips while the port is open.
When the housing comprises a shaft, e.g. in the case of a device for use in endoscopic surgery, the port of the shaft may, for example, be present at its distal end face or a side port may be provided in the wall of the shaft near its distal end. In the first form, the shaft can be pushed onto a body passageway before a clip is expelled onto the body passageway. However, in this configuration the surgeon""s endoscopic view of the body passageway may be obscured by the shaft of the apparatus of the present invention. In the second form, which may avoid this disadvantage, the apparatus may be brought alongside the body passageway before the apparatus is actuated.
The apparatus may be constructed from any convenient materials. Metals such as, for example, stainless steel may be used. Plastic polymers such as, for example, ultrahigh molecular weight polyethylene or polyacetyl may be used. Of course, different materials may be used for different parts. Metal is preferred for the internal mechanism, with plastic preferred for the outer housing.
As mentioned above, the apparatus may conveniently be provided with a proximal handle whereby the surgeon can hold the apparatus. The clip control device and, if present, cover control device are preferably actuable via a single finger trigger or button associated with the handle. The ergonomically configured handles and finger-control systems described in WO-97/42884 are particularly suitable, and the disclosure of that earlier publication is incorporated herein by reference.
Moreover, when used in endoscopic surgery, the device may conveniently be used with the improved instrument support systems for endoscopic surgery described in WO-97/42884.
The apparatus may suitably be provided in disposable and reusable parts, which are releasably connectable together for use. The xe2x80x9cdisposablexe2x80x9d part(s) is/are suitably provided in sterile individual packs, and the xe2x80x9creusablexe2x80x9d part(s) is/are suitably provided in sterilisable materials and in an sterilisable configuration.
The disposable part(s) may suitably include the clips, and may for example comprise at least a major portion of the shaft of the housing in the preferred apparatus form. The clips may be pre-loaded in the shaft, so that all that is necessary for the surgeon or his or her assistant to do is to connect the disposable shaft to the reusable handle part. Alternatively, the disposable part may comprise a magazine or cartridge of clips, which is loaded into reusable apparatus.
Where it is convenient, and where suitable laboratory or workshop facilities are available the xe2x80x9cdisposablexe2x80x9d part(s) may in fact be made recyclable, e.g. reloadable With clips, resettable into the ready-for-use configuration, and resterilisable.
One particular surgical method for occluding or encircling a body passageway, enabled by the apparatus of the present invention, generally comprises:
(a) providing a clip comprising an elongate element having first and second ends and an intermediate central portion, the clip comprising a temperature dependent shape memory material and being resiliently movable, in response to an increase in temperature from a first temperature, substantially below body temperature, to body temperature, under an inherent biassing force from a first configuration, in which the ends are spaced apart to allow the body passageway to pass therebetween, to a second configuration in which the clip is deformed on itself so that the clip grips or encircles the body passageway, the clip being provided at the first temperature and in the first configuration thereof;
(b) offering the clip to the body passageway so that the body passageway is received substantially between the ends of the clip; and
(c) allowing the temperature of the clip to rise to approach body temperature by the proximity of the body passageway to the clip, whereby the clip deforms into its second configuration around the body passageway.
In another aspect, the surgical method for occluding or encircling a body passageway, using the apparatus of the present invention, generally comprises:
(a) locating the surgical apparatus such that the port of the housing is in proximity to the body passageway;
(b) operating the clip control device to cause a clip to be expelled from the port of the housing of the apparatus, whereby upon release in its first configuration from the apparatus the clip resiliently deforms itself onto the body passageway to occlude or encircle the body passageway; and
(c) removing the apparatus from proximity to the body passageway.